A major goal in the pharmacological arts has been the development of methods and compositions to facilitate the specific delivery of therapeutic and other agents to the appropriate cells and tissues that would benefit from such treatment, and the avoidance of the general physiological effects of the inappropriate delivery of such agents to other cells or tissues of the body. One common example of the need for such specificity is in the field of neurologic agent therapy for the treatment of diseases of the central nervous system, particularly the brain, which is protected by a layer of endothelial cells and other structures collectively known as the blood-brain barrier. In the pharmacological and neurologic arts, it is well-recognized that the inability to deliver effective amounts of neurotropic, psychotropic and anticonvulsant drugs and agents across the blood-brain barrier severely limits the therapeutic efficacy of such pharmaceutical compounds and can prevent treatment of neurologic disease. In addition, the use of even effective neurologic agents is further limited by systemic toxicity resulting from the high systemic concentrations that must be administered to achieve a therapeutic concentration of such agents in the brain, central nervous system and other neurological structures. Similar considerations apply in other organs and tissues in mammals that are protected by such blood-related barriers, such as the testes.
In addition, it is recognized in the medical arts that certain subcellular organelles are the sites of pharmacological action of certain drugs or are involved in the biological response to certain stimuli. Specific delivery of diagnostic or therapeutic compounds to such intracellular organelles is thus desirable to increase the specificity and effectiveness of such clinical diagnostic or therapeutic techniques.
Drug Targeting
It is desirable to increase the efficiency and specificity of administration of a therapeutic agent to the cells of the relevant tissues protected by physiological barriers (i.e., such as the blood-brain barrier) in a variety of pathological states. This is particularly important as relates to psychotropic, neurological and neurotropic agents. Such agents typically have systemic effects, including renal and hepatotoxicity, hematopoietic suppression, teratogenic capacity, partitioning into breast milk and other pleiotropic cytotoxic effects that damage or otherwise deleteriously impact on uninvolved cells and tissues. This is particularly the case in delivering psychotropic, neurotropic and neurological agents to physiologically protected sites, since high systemic concentrations of such agents are required to promote partitioning of a sufficient amount of the psychotropic, neurotropic and neurological agents into the protected sites to achieve a therapeutic result. Thus, an efficient delivery system which would enable the delivery of such drugs specifically to cells and tissues in such physiologically protected sites would increase the efficacy of treatment and reduce the associated xe2x80x9cside effectsxe2x80x9d of such drug treatments, and also serve to reduce morbidity and mortality associated with clinical administration of such drugs.
Numerous methods for enhancing the biological activity and the specificity of drug action have been proposed or attempted (see, for example, Kreeger, 1996, The Scientist, Sep. 16, 1996, p. 6). To date, however, efficient or specific drug delivery remains to be predictably achieved.
U.S. Pat. No. 5,017,566, issued May 21, 1991 to Bodor disclose xcex2- and xcex3-cyclodextrin derivatives comprising inclusion complexes of lipoidal forms of dihydropyridine redox targeting moieties.
U.S. Pat. No. 5,023,252, issued Jun. 11, 1991 to Hseih disclose the use of pharmaceutical compositions comprising a neurologically active drug and a compound for facilitating transport of said drug across the blood-brain barrier including a macrocyclic ester, diester, amide, diamide, amidine, diamidine, thioester, dithioester, thioamide, ketone or lactone.
U.S. Pat. No. 5,024,998, issued Jun. 18, 1991 to Bodor disclose parenteral solutions of aqueous-insoluble drugs with xcex2- and xcex3-cyclodextrin derivatives.
U.S. Pat. No. 5,039,794, issued Aug. 13, 1991 to Wier et al. disclose the use of a metastatic tumor-derived egress factor for facilitating the transport of compounds across the blood-brain barrier.
U.S. Pat. No. 5,112,863, issued May 12, 1992 to Hashimoto et al. disclose the use of N-acyl amino acid derivatives as antipsychotic drugs for delivery across the blood-brain barrier.
U.S. Pat. No. 5,124,146, issued Jun. 23, 1992 to Neuwelt disclose a method for delivery of therapeutic agents across the blood-brain barrier at sites of increase permeability associated with brain lesions.
U.S. Pat. No. 5,153,179, issued Oct. 6, 1992 to Eibl disclose acylated glycerol and derivatives for use in a medicament for improved penetration of cell membranes.
U.S. Pat. No. 5,177,064, issued Jan. 5, 1993 to Bodor disclose the use of lipoidal phosphonate derivatives of nucleoside antiviral agents for delivery across the blood-brain barrier.
U.S. Pat. No. 5,254,342, issued Oct. 19, 1993 to Shen et al. disclose receptor-mediated transcytosis of the blood-brain barrier using the transferrin receptor in combination with pharmaceutical compounds that enhance or accelerate this process.
U.S. Pat. No. 5,258,402, issued Nov. 2, 1993 to Maryanoff disclose treatment of epilepsy with imidate derivatives of anticonvulsive sulfamate.
U.S. Pat. No. 5,270,312, issued Dec. 14, 1993 to Glase et al. disclose substituted piperazines as central nervous system agents.
U.S. Pat. No. 5,284,876, issued Feb. 8, 1994 to Shashoua et al., disclose fatty acid conjugates of dopanergic drugs for tardive dyskinesia.
U.S. Pat. No. 5,389,623, issued Feb. 14, 1995 to Bodor disclose the use of lipoidal dihydropyridine derivatives of anti-inflammatory steroids or steroid sex hormones for delivery across the blood-brain barrier.
U.S. Pat. No. 5,405,834, issued Apr. 11, 1995 to Bundgaard et al. disclose prodrug derivatives of thyrotropin releasing hormone.
U.S. Pat. No. 5,413,996, issued May 9, 1995 to Bodor disclose acyloxyalkyl phosphonate conjugates of neurologically-active drugs for anionic sequestration of such drugs in brain tissue.
U.S. Pat. No. 5,434,137, issued Jul. 18, 1995 to Black disclose methods for the selective opening of abnormal brain tissue capillaries using bradykinin infused into the carotid artery.
U.S. Pat. No. 5,442,043, issued Aug. 15, 1995 to Fukuta et al. disclose a peptide conjugate between a peptide having a biological activity and incapable of crossing the blood-brain barrier and a peptide which exhibits no biological activity and is capable of passing the blood-brain barrier by receptor-mediated endocytosis.
U.S. Pat. No. 5,466,683, issued Nov. 14, 1995 to Sterling et al. disclose water soluble analogues of the anticonvulsant Tegretol(copyright) (carbamazepine) for the treatment of epilepsy.
U.S. Pat. No.5,525,727, issued Jun. 11, 1996 to Bodor disclose compositions for differential uptake and retention in brain tissue comprising a conjugate of a narcotic analgesic and agonists and antagonists thereof with a lipoidal form of dihydropyridine that forms a redox salt upon uptake across the blood-brain barrier that prevents partitioning back to the systemic circulation thereafter.
International Patent Application Publication Number WO85/02342, published Jun. 6, 1985 for Max-Planck Institute disclose a drug composition comprising a glycerolipid or derivative thereof.
International Patent Application Publication Number WO89/11299, published Nov. 30, 1989 for State of Oregon disclose a chemical conjugate of an antibody with a an enzyme which is delivered specifically to a brain lesion site for activating a separately-administered neurologically-active prodrug.
International Patent Application Publication Number WO91/04014, published Apr. 4, 1991 for Synergen, Inc. disclose methods for delivering therapeutic and diagnostic agents across the blood-brain barrier by encapsulating said drugs in liposomes targeted to brain tissue using transport-specific receptor ligands or antibodies.
International Patent Application Publication Number WO91/04745, published Apr. 18, 1991 for Athena Neurosciences, Inc. disclose transport across the blood-brain barrier using cell adhesion molecules and fragments thereof to increase the permeability of tight junctions in vascular endothelium.
International Patent Application Publication Number WO91/14438, published Oct. 3, 1991 for Columbia University disclose the use of a modified, chimeric monoclonal antibody for facilitating transport of substances across the blood-brain barrier.
International Patent Application Publication Number WO94/0113 1, published Jan. 20, 1994 for Eukarion, Inc. disclose lipidized proteins, including antibodies. International Patent Application Publication Number WO94/03424, published Feb. 17, 1994 for Ishikura et al. disclose the use of amino acid derivatives as drug conjugates for facilitating transport across the blood-brain barrier.
International Patent Application Publication Number WO94/06450, published Mar. 31, 1994 for the University of Florida disclose conjugates of neurologically-active drugs with a dihydropyridine-type redox targeting moiety and comprising an amino acid linkage and an aliphatic residue.
International Patent Application Publication Number WO94/02178, published Feb. 3, 1994 for the U.S. Government, Department of Health and Human Services disclose antibody-targeted liposomes for delivery across the blood-brain barrier.
International Patent Application Publication Number WO95/07092, published Mar. 16, 1995 for the University of Medicine and Dentistry of New Jersey disclose the use of drug-growth factor conjugates for delivering drugs across the blood-brain barrier.
International Patent Application Publication Number WO96/00537, published Jan. 11, 1996 for Southern Research Institute disclose polymeric microspheres as injectable drug-delivery vehicles for delivering bioactive agents to sites within the central nervous system.
International Patent Application Publication Number WO96/04001, published Feb. 15, 1996 for Molecular/Structural Biotechnologies, Inc. disclose omega-3-fatty acid conjugates of neurologically-active drugs for brain tissue delivery.
International Patent Application Publication Number WO96/22303, published Jul. 25, 1996 for the Commonwealth Scientific and Industrial Research Organization disclose fatty acid and glycerolipid conjugates of neurologically-active drugs for brain tissue delivery.
An additional challenge in designing an appropriate drug delivery scheme is to include within the drug conjugate a functionality which could either accelerate or reduce the rate at which the drug is released upon arrival at the desired site. Such a functionality would be especially valuable if it allowed differential rates of drug release, or specific release only at the appropriate drug target site.
There remains a need in the art for an effective means for the specific delivery of biologically-active compounds, particularly psychotropic, neurotropic and neurological drugs and agents, to physiologically restricted or protected sites. Advantageous embodiments of such delivery means are formulated to efficiently deliver the biologically-active compound to a physiologically-protected site, such as the brain or central nervous system, while minimizing hepatic and renal uptake of the agent or hematopoietic insult resulting therefrom.
The present invention is directed to an improved method for delivering biologically-active compounds, particularly drugs including preferably psychotropic, neurotropic and neurologically-acting drugs, to physiologically protected sites in an animal in vivo. This delivery system achieves specific delivery of such biologically-active compounds through conjugating the compounds with a polar lipid carrier. This invention has the specific advantage of facilitating the entry of such compounds into cells and tissues protected by such physiological barriers as the blood-brain barrier via a polar lipid carrier, achieving effective intracellular concentration of such compounds more efficiently and with more specificity than conventional delivery systems.
The invention provides compositions of matter comprising a biologically-active compound covalently linked to a polar lipid carrier molecule. Preferred embodiments also comprise a spacer molecule having two linker functional groups, wherein the spacer has a first end and a second end and wherein the lipid is attached to the first end of the spacer through a first linker functional group and the biologically-active compound is attached to the second end of the spacer through a second linker functional group. In preferred embodiments, the biologically-active compound is a drug, most preferably a psychotropic, neurotropic or neurologically-acting drug or agent, or an antioxidant. Preferred polar lipids include but are not limited to acyl- and acylated carnitine, sphingosine, ceramide, phosphatidyl choline, phosphatidyl glycerol, phosphatidyl ethanolamine, phosphatidyl inositol, phosphatidyl serine, cardiolipin and phosphatidic acid. Preferred biologically-active compounds include neurotropic agents such as L-dopa, hydroxytryptamine and metabolites thereof; amantadine, benztropine, bromocryptine, diphenhydramine, levadopa (a particularly preferred embodiment) and combinations thereof (e.g., with carbidopa as provided as Sinemet(copyright)); pergolid, trihexphenidyl, ethosuximide, valproic acid, carbamazepine (e.g., Tegretol(copyright)) and, in a particularly preferred embodiment, the 10- or 11-hydroxy analogues of carbamazepine; primidone, gabapentin in a particularly preferred embodiment; lamotrigine in a particularly preferred embodiment; felbamate, paramethadione and trimethadione; phenothiazines, thioxanthemes and related compounds; clozapine, haldoperidol, loxapine (Loxitane(copyright)), benzodiazapene antidepressants of the norepinephrine reuptake inhibitor type; monoamine oxidase inhibitors, and antioxidants such as carotenes, glutathione and N-acetylcysteine. Pharmaceutical compositions comprising the drug/polar lipid conjugates of the invention are also provided.
The invention also provides compositions of matter comprising a biologically-active compound covalently linked to a lipid, most preferably a polar lipid, carrier molecule via a spacer molecule wherein the spacer allows the biologically-active compound to act without being released at an intracellular site. In these embodiments of the invention, the first linker functional group attached to the first end of the spacer is characterized as xe2x80x9cstrongxe2x80x9d and the second linker functional group attached to the second end of the spacer is characterized as xe2x80x9cweakxe2x80x9d, with reference to the propensity of the covalent bonds between each end of the spacer molecule to be broken. In other embodiments of the compositions of matter of the invention, the spacer allows the facilitated hydrolytic release of the biologically-active compound at an intracellular site. Other embodiments of the spacer facilitate the enzymatic release of the biologically-active compound at an intracellular site. In particularly preferred embodiments, the spacer functional group is hydrolyzed by an enzymatic activity found in brain tissue, including neuronal, glial and other brain cell types, preferably an esterase and most preferably an esterase having a differential expression and activity profile in the appropriate target cell type. In additional preferred embodiments, specific release of biologically-active compounds is achieved by enzymatic or chemical release of the biologically-active compound by extracellular cleavage of a cleavable linker moiety via an enzymatic activity specific for brain tissue, with resulting specific uptake of the released psychotropic, neurotropic or neurological agent by the appropriate cell in said tissue.
In another embodiment of this aspect of the invention, the spacer molecule is a peptide of formula (amino acid)n, wherein n is an integer between 2 and 25, preferably wherein the peptide comprises a polymer of one or more amino acids. In other embodiments of the compositions of matter of the invention, the biologically-active compound of the invention has a first functional linker group, and a lipid, most preferably a polar lipid, carrier has a second functional linker group, and the compound is covalently linked directly to the lipid carrier by a chemical bond between the first and second functional linker groups. In preferred embodiments, each of the first and second functional linker groups is a hydroxyl group, a primary or secondary amino group, a phosphate group or substituted derivatives thereof or a carboxylic acid group. In another aspect of the invention is provided compositions of matter comprising a drug, most preferably an a psychotropic, neurotropic or neurological drug or agent, covalently linked to a polar lipid carrier molecule. Preferred embodiments also comprise a spacer molecule having two linker functional groups, wherein the spacer has a first end and a second end and wherein the lipid is attached to the first end of the spacer through a first linker functional group and the drug is attached to the second end of the spacer through a second linker functional group. Preferred embodiments of the invention are provided wherein the drug is a psychotropic, neurotropic or neurological drug or agent. Preferred polar lipids include but are not limited to acyl- and acylated carnitine, sphingosine, ceramide, phosphatidyl choline, phosphatidyl glycerol, phosphatidyl ethanolamine, phosphatidyl inositol, phosphatidyl serine, cardiolipin and phosphatidic acid. Preferred psychotropic, neurotropic or neurological drugs or agents comprising the conjugates of the invention include L-dopa, hydroxytryptamine and metabolites thereof; amantadine, benztropine, bromocryptine, diphenhydramine, levadopa (a particularly preferred embodiment) and combinations thereof (e.g., with carbidopa as provided as Sinemet(copyright)); pergolid, trihexphenidyl, ethosuximide, valproic acid, carbamazepine (e.g., Tegretol(copyright)) and, in a particularly preferred embodiment, the 10- or 11-hydroxy analogues of carbamazepine; primidone, gabapentin in a particularly preferred embodiment; lamotrigine in a particularly preferred embodiment; felbamate, paramethadione and trimethadione; phenothiazines, thioxanthemes and related compounds; clozapine, haldoperidol, loxapine (Loxitane(copyright)), benzodiazapene antidepressants of the norepinephrine reuptake inhibitor type; monoamine oxidase inhibitors, and antioxidants such as carotenes, glutathione and N-acetylcysteine. Pharmaceutical compositions comprising the drug/polar lipid conjugates of the invention are also provided.
The invention also provides compositions of matter comprising a psychotropic, neurotropic or neurological drug or agent, covalently linked to a polar lipid carrier molecule via a spacer molecule, wherein the spacer allows the drug to act without being released at an intracellular site. In these embodiments of the invention, the first linker functional group attached to the first end of the spacer is characterized as xe2x80x9cstrongxe2x80x9d and the second linker functional group attached to the second end of the spacer is characterized as xe2x80x9cweakxe2x80x9d, with reference to the propensity of the covalent bonds between each end of the spacer molecule to be broken.
In other embodiments of the compositions of matter of the invention, the spacer allows the facilitated hydrolytic release of a psychotropic, neurotropic or neurological drug or agent at an intracellular site. Other embodiments of the spacer facilitate the enzymatic release of the psychotropic, neurotropic or neurological drug or agent of the invention at an intracellular site. In particularly preferred embodiments, the spacer functional group is hydrolyzed by an enzymatic activity found in a physiologically-protected site, such as the brain and central nervous system and more particularly including neuronal, glial and other brain cell types, wherein said enzymatic activity is preferably an esterase and most preferably an esterase having a differential expression and activity profile in different tissue cell types. In additional preferred embodiments, specific release of the psychotropic, neurotropic or neurological drug or agent of the invention is achieved by enzymatic or chemical release of these drugs by extracellular cleavage of a cleavable linker moiety via an enzymatic activity specific for,for example, brain tissue, followed by specific uptake of the released psychotropic, neurotropic or neurological drug or agent by the appropriate cell in said tissue.
In another embodiment of this aspect of the invention, the spacer molecule is a peptide of formula (amino acid)n, wherein n is an integer between 2 and 25, preferably wherein the peptide comprises a polymer of one or more amino acids.
In still further embodiments of the compositions of matter of the invention are provided psychotropic, neurotropic or neurological drugs or agents having a first functional linker group, and a polar lipid carrier having a second functional linker group, wherein the drug is covalently linked directly to the polar lipid carrier by a chemical bond between the first and second functional linker groups. In preferred embodiments, each of the first and second functional linker groups is a hydroxyl group, a primary or secondary amino group, a phosphate group or substituted derivatives thereof or a carboxylic acid group. Preferred psychotropic, neurotropic or neurological drugs or agents comprising the conjugates of the invention include L-dopa, hydroxytryptamine and metabolites thereof; amantadine, benztropine, bromocryptine, diphenhydramine, levadopa (a particularly preferred embodiment) and combinations thereof (e.g., with carbidopa as provided as Sinemet(copyright)); pergolid, trihexphenidyl, ethosuximide, valproic acid, carbamazepine (e.g., Tegretol(copyright)) and, in a particularly preferred embodiment, the 10- or 11-hydroxy analogues of carbamazepine; primidone, gabapentin in a particularly preferred embodiment; lamotrigine in a particularly preferred embodiment; felbamate, paramethadione and trimethadione; phenothiazines, thioxanthemes and related compounds; clozapine, haldoperidol, loxapine (Loxitane(copyright)), benzodiazapene antidepressants of the norepinephrine reuptake inhibitor type; monoamine oxidase inhibitors, and antioxidants such as carotenes, glutathione and N-acetylcysteine. Preferred polar lipids include but are not limited to acyl- and acylated camitine, sphingosine, ceramide, phosphatidyl choline, phosphatidyl glycerol, phosphatidyl ethanolamine, phosphatidyl inositol, phosphatidyl serine, cardiolipin and phosphatidic acid. Pharmaceutical compositions comprising the drug/polar lipid conjugates of the invention are also provided.
Preferred embodiments of this aspect of the invention include compositions of matter that are polar lipid conjugates of anticonvulsive agents, antiparkinsonian drugs, alkaloids, catecholamines including dopamine analogues and derivatives, muscarinic receptor agonists and antagonists, cholinergic receptor agonists and antagonists, calcium channel blockers, xcex3-aminobutyric acid (GABA) receptor agonists, antagonists, and uptake inhibitors and enhancers; phenothiazines, thioxanthemes and related compounds; clozapine, haldoperidol, loxapine (Loxitane(copyright)), benzodiazapene antidepressants of the norepinephrine reuptake inhibitor type; monoamine oxidase inhibitors; antidepressants and antimanic agents, antioxidants and other compounds that mitigate the effects of reactive oxygen species (for the treatment of Alzheimer""s disease, Parkinson""s disease, or other neurodegenerative conditions such as ataxia telangiectasia and amyelolaterosclerosis (ALS)).
As disclosed herein, the invention comprehends a polar lipid-drug conjugate wherein the polar lipid selectively promotes association with and transit across certain physiological barriers to protected tissue sites, thereby facilitating delivery of drugs and other pharmaceutical agents to such physiologically restricted or protected sites. In embodiments comprising a spacer moiety, the spacer component of the conjugates of the invention will preferably act to specifically release the drug from the lipid at the target site; prevent the non-specific release from the drug from the lipid in the systemic circulation or in hepatic, renal or other inappropriate cells, tissue or organs; target the conjugate to a specific cell or cell type within the protected tissue; prevent interaction and/or uptake of the drug by hematopoietic, ocular, hepatic or renal tissues; or perform other functions to maximize the effectiveness of the drug.
This type of conjugate has numerous advantages. The drug-lipid conjugates of the invention provide delivery of a variety of psychotropic, neurotropic and neurological drugs and agents to physiologically restricted or protected sites in vivo at concentrations and pharmicokinetic rates not heretofore attainable. A benefit of this advantage is the achievement of therapeutic indices of agents in such protected sites whereby the agent is useful for achieving a desired therapeutic goal. Another benefit is decreased hepatic toxicity, hematopoietic suppression (such as thrombocytopenia, leukopenia, a plastic anemia, leukocytosis, eosinophilia, pancytopenia, agranulocytosis), reduced systemic metabolism, degradation and toxicity, reduced hepatic clearance, reduced systemic adverse drug interactions, and generally reduced side effects due to the achievement of a lower, therapeutically-effective dose as the result of surmounting the physiological barrier. These biological effects can also result in simplified dosage schedules, particularly for drugs with short systemic half-lives.
In addition, the lipid/drug conjugates promote the intracellular entry of a variety of potentially useful drugs at pharmokinetic rates not currently attainable. The range of targeted cell types is not limited per se by particular, limited biological properties of the cell (such as the number and type of specific receptor molecules expressed on the cell surface). In contrast to traditional attempts to simply target drugs to specific cells, the conjugates of the invention can also target drugs to specific intracellular organelles and other intracellular compartments. In certain preferred embodiment, the conjugates of the invention incorporate a variable spacer region that may allow pharmacologically-relevant rates of drug release from polar lipid carrier molecules to be engineered into the compositions of the invention, thereby increasing their clinical efficacy and usefulness. Thus, time-dependent drug release and specific drug release in cells expressing the appropriate degradative enzymes are a unique possibility using the drug-lipid conjugates of the invention.
In particular, felicitous design of the psychotropic, neurotropic/neurological drug/spacer/polar lipid conjugate can provide an in vivo reservoir of time-dependent drug release in the physiologically protected tissue, resulting in specific delivery of therapeutic amounts to such tissues using a reduced dosage regime to minimize nonspecific, systemic and deleterious side effects. In such formulations, the amount and activity of the psychotropic, neurotropic or neurological drug can be modulated by release via cleavage, preferably hydrolytic cleavage, of the spacer moiety, most preferably by an enzymatic activity in the protected tissue (e.g., brain) that has a differential pattern of expression or activity in different cell types in said tissue. The conjugates of the invention can also be combined with other drug delivery approaches to further increase specificity and to take advantage of useful advances in the art.
Specific preferred embodiments of the present invention will become evident from the following more detailed description of certain preferred embodiments and the claims.